This mattress was purchased to replace a Serta waterbed mattress that was over 20 years old. It fit like a glove into my waterbed frame and is a perfect comfort level for me. It is firm but not hard. I sleep without having to change positions every few hours. Warm after a minute - which I was afraid I'd miss without a heater as in my waterbed. It shipped in a box that I could handle myself to get upstairs, opened, and into the frame. Unlike the waterbed mattress that was too heavy for me to get out and really troublesome to drain.